The present invention relates to an apparatus for counting flexible flat products arranged in an overlapping formation, especially printed products.
An apparatus of this type is disclosed by EP-A-0 408 490. A conveying device, constructed as a belt conveyor and driven at a conveying speed in a conveying direction, is intended to convey printed products arranged in a regular overlapping formation, in which each printed product rests on the preceding one, past a detection device. The latter has a slide which is driven alternatingly in and counter to the conveying direction by means of a drive, matched to a system cycle rate at which the printed products are conveyed, and on which a contact element is arranged. If the slide is moved in the conveying direction at a speed which is higher than the conveying speed, when the contact element catches up with an object it comes into contact with the rear edge of the latter. Because of the higher speed of the slide in relation to the conveying speed, the contact element is deflected mechanically by a force directed counter to the conveying direction. This deflection of the contact element is registered by means of a detection means likewise arranged on the slide, a signal being emitted to a counter. This known apparatus is not really suitable for counting thin objects. In addition, in order to deflect the contact element a certain force is needed which, in particular in the case of thin objects, could damage the rear edge. If no specific measures are taken, there is also the risk that the objects can be displaced because of the action of the contact element.
It is an object of the present invention to provide a generic apparatus which is suitable for the precise counting even of thin objects.
The above and other objects and advantages of the present invention are achieved by the provision of an apparatus which comprises a conveying device for conveying the objects in an overlapping formation, and a detection device which includes an activation element which is moved cyclically during at least a portion of its movement path in the conveying direction and at a speed higher than the conveying speed, so as to be brought into interaction with a rear region of each object conveyed past the detection device. The detection device further includes a detection element which emits a signal to a counter when the activation element interacts with the respective object.
The activation element is constructed as an insertion element which is inserted into the rear end region of the respective object or between the object and the following object. The insertion element and the detection element create a counting barrier for each object. The same effect is achieved as if the objects were conveyed individually through the counting barrier, although they are conveyed in an overlapping formation. The objects to be counted trigger the generation of the signal themselves directly because of their presence in the counting barrier between the insertion element and the detection element. As a result, the action of force on the rear edge of the objects can be avoided, or at least can be kept extremely small.